Polycarbonates made using highly selective catalysts

ABSTRACT

Poly(propylene carbonates) are prepared from propylene oxide and CO 2  with less than 10% cyclic propylene carbonate by product using cobalt based catalysts of structure 
                         
preferably in combination with salt cocatalyst, very preferably cocatalyst where the cation is PPN +  and the anion is Cl −  or OBzF 5   − . Novel products include poly(propylene carbonates) having a stereoregularity greater than 90% and/or a regioregularity of greater than 90%.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/976,800, filed Oct. 29, 2007, which is a divisional of U.S. patentapplication Ser. No. 11/244231 (now U.S. Pat. No. 7,304,172), filed Oct.6, 2005, which claims the benefit of U.S. Provisional Application No.60/616,630, filed Oct. 8, 2004, the entire contents of each of which areincorporated herein by reference.

The invention was made at least in part with U.S. Government supportunder National Science Foundation Contract No. DMR-0079992. The U.S.Government has certain rights in the invention.

TECHNICAL FIELD

The invention is directed at high selectivity cobalt containingcatalysts for producing poly(alkylene carbonates) from alkylene oxideand carbon dioxide, to a process for producing polycarbonates using thecatalysts and to polycarbonates produced thereby.

BACKGROUND OF THE INVENTION

The generalized mechanism of CO₂/epoxide copolymerization involves twosteps, namely epoxide ring opening by a metal carbonate followed by CO₂insertion into a metal alkoxide. When aliphatic epoxides such aspropylene oxide are used, a common side-product is the cyclic carbonate.The most active catalysts, namely [Zn(BDI)OAc] and [Cr(salph)Cl]/DMAP,reported to date, produce 10-30% of unwanted cyclic propylene carbonate(CPC) by-product, under optimized conditions.

SUMMARY OF THE INVENTION

It has been discovered herein that catalysts of sufficient activity forcommercial production and which have selectivity of greater than 90:1poly(propylene carbonate) (PPC) to CPC, often greater than 99:1 PPC toCPC, are enantiomerically pure cobalt catalysts, e.g., (salen)Co^(III)(X) complexes and the like.

In a first embodiment herein, there are provided cobalt containingcompounds useful as catalysts for CO₂/C₂-C₁₀ alkylene oxidecopolymerization with little or no cyclic alkylene carbonate by-product.These compounds have the structural formula:

where R¹ is a hydrocarbon bridge which may be substituted with C₁-C₂₀alkyl, C₁-C₂₀ alkoxy, halogen (e.g., Cl, Br, I), nitro, cyano or amine;where R², R³ and R⁴ can be the same or different and are selected fromthe group consisting of H, C₁-C₂₀ alkyl, C₆-C₂₀ aryl, and C₁-C₂₀fluorocarbon and where R² and R³ or R³ and R⁴ can form a ring which canbe substituted with H, C₁-C₂₀ alkyl, C₆-C₂₀ aryl, C₁-C₂₀ alkyl C₆-C₂₀aryl substituted with C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, phenoxy, C₁-C₂₀carboxylate, C₁-C₂₀ acyl, amino, C₁-C₂₀ fluoroalkyl, cyano, nitro orhalogen (e.g., Cl, Br, I) or a solid support and where X is anynucleophile which can ring open an epoxide.

The term “solid support” as used herein refers to a soluble or insolublepolymeric structure, such as crosslinked polystyrene, or an inorganicstructure, e.g., of silica or alumina.

The cases of X being nitro-substituted phenoxide are excluded when R¹ is1,2-cyclohexanediyl to avoid disclosure in Lu, X-B, et al, Angew. Chem.Int. Ed 43, 3574-3577 (2004).

For the structure where X is Br, R¹ is ethyl and R³ and R⁴ form a phenylring, the case is excluded where the substituents on the phenyl ring oncarbons which are not also part of another ring, are all H, because thiscompound has been found to be inactive in producing poly(propylenecarbonate).

For the structure where X is Br, R¹ is 1,2-cyclohexanediyl and R³ and R⁴form a phenyl ring, the case is excluded where substituents on carbon onthe phenyl ring which is not also part of another ring and is closest toO is not H, because this compound has been found to be inactive inproducing poly(propylene carbonate).

In another embodiment, denoted the second embodiment, there is provideda catalyst system for use in catalyzing the copolymerization of C₂-C₁₀alkylene oxide, and carbon dioxide to produce poly(C₂-C₁₀ alkylenecarbonate), e.g., poly(propylene carbonate), with less than 10% cyclicalkylene carbonate, e.g., cyclic propylene carbonate, by-product,comprising compound of the first embodiment as catalyst and a saltcocatalyst which is bulky and non-coordinating where the cation is anybulky cation, e.g., a phosphorus and/or nitrogen based cation, e.g.,[R₄N]⁺, [R₄N]⁺, [R₃P═N═PR₃]⁺ or [P[NR₃]₃]³⁺ where R is C₁-C₂₀ alkyl orC₆-C₂₀ aryl or a solid support, where the unsupported cation or theionic portion of a supported cation has a molecular weight ranging, forexample, from 750 g/mol to 2000 g/mol, and the anion is a nucleophilewhich can ring open an epoxide, and the R groups can be the same ordifferent.

In another embodiment, denoted the third embodiment, there is provided amethod for preparing poly(C₂-C₁₀ alkylene carbonate)s, e.g.,poly(propylene carbonate), by copolymerization of C₂-C₁₀ alkylene oxide,e.g., propylene oxide, and carbon dioxide with less than 10% cyclicC₂-C₁₀ alkylene carbonate, e.g. cyclic propylene carbonate, by-product,comprising the step of reacting C₂-C₁₀ alkylene oxide and carbon dioxideat a CO₂ pressure ranging from 1 to 1,000 psi, a reaction temperature of0 to 150° C. and a reaction time of 0.1 to 50 hours, in the presence ofa catalyst which is compound of the first embodiment at alkylene oxideto catalyst ratio on a cobalt basis ranging from 200:1 to 100,000:1

In another embodiment, denoted the fourth embodiment, there is provideda method for preparing poly(C₂-C₁₀ alkylene carbonate), e.g.,poly(propylene carbonate), with less than 10% cyclic alkylene carbonate,e.g., cyclic propylene carbonate by-product, comprising the step ofreacting C₂-C₁₀ alkylene oxide, e.g., propylene oxide, and CO₂ at a CO₂pressure ranging from 1 psi to 300 psi, a reaction temperature of 0 to100° C., and a reaction time of 0.1 to 50 hours, e.g., 0.5 to 4 hours,in the presence of the catalyst system of the second embodiment, wherethe ratio of alkylene oxide to cocatalyst to catalyst ranges from500-100,000:0.5-1.5:0.5-1.5

In another embodiment, denoted the fifth embodiment, there is providedpoly(propylene carbonate) of M_(n) ranging from 500 to 1,000,000 g/moland polydispersity index (PDI) ranging from 1.05 to 5.0, e.g., 1.05 to1.30, with greater than 90% head-to-tail linkages. In one case, thepolymer has random stereochemistry. In another case, more than 90% ofadjacent stereocenters have the same relative stereochemistry(isotactic).

In another embodiment, denoted the sixth embodiment, there is providedpoly(propylene carbonate) of M_(n) ranging from 500 to 1,000,000 g/moland PDI ranging from 1.05 to 5.0, e.g., 1.05 to 1.30, where greater than90% of the stereocenters are of the same stereochemistry.

The molecular weight of the polycarbonate can be increased within thestated range by longer polymerization times. The molecular weight of thepolycarbonate can be decreased within the range by the addition of chaintransfer agents in the form of carboxylic acids (e.g. pentafluorobenzoicacid), alcohols (e.g. methanol), dicarboxylic acids, diols, poly acids,polyols, and their deprotonated forms (e.g., sodium pentafluorobenzoate)and other additives known to promote chain transfer. The polymerizationcan also be conducted in solvent.

-   -   M_(n) and PDI here are determined by gel permeation        chromatography in tetrahydrofuran at 40° C., calibrated with        polystyrene standards.

DETAILED DESCRIPTION

In an example of the first embodiment

in the structure (I) is selected from the group consisting of:

where R⁵ and R⁶ can be the same or different and are H, C₁-C₂₀ alkyl,C₆-C₂₀ aryl, halogen (e.g., F, Cl, Br, I), nitro, cyano, C₁-C₂₀ alkoxyor amine.

X in the formula (I) can be selected, for example, from the groupconsisting of C₁-C₂₀ alkyl, halogen (e.g., Cl, Br, I), C₁-C₂₀ amido,cyano, azide, C₁-C₂₀ alkyl carboxylate, C₆-C₂₀ aryl carboxylate, C₁-C₂₀alkoxide and phenoxide.

In one case, the compounds have the structure:

where R is selected from the group consisting of Br, H and ^(t)Bu.

In an overlapping case, the compounds have the structure

where X is Br, Cl, I, OAc, OBzCF₃ (p-trifluoromethylbenzoate) or OBzF₅where OBzF₅ is 2,3,4,5,6-pentafluorobenzoate. The compound of structure(VIII) where X is OBzF₅ is novel.

In still another case, the compounds have the structure

where R¹¹ is ^(t)Bu and R¹⁰ is selected from the group consisting of H,Br and OMe; R¹¹ is Me and R¹⁰ is H; or R¹¹ is CPh(CH₃)₂ and R¹⁰ isCPh(CH₃)₂. The compounds are novel.

In still another case, the compound has the structure

This compound is novel.

-   -   In yet another case, the compounds have the structure

where R⁷ is Me, R⁸ is H and R⁹ is H; or where R⁷ is Me, R⁸ is Me and R⁹is H; or where R⁷ is Ph, R⁸ is H and R⁹ is Ph.

The cobalt carboxylate compounds are made by adding oxygen and theappropriate carboxylic acid to the (salen)Co(II) complex. The cobalthalide compounds are made by reacting (salen)Co(III) tosylate complexwith the appropriate sodium halide.

The term “salen” means any tetradentate ligand derived from a diamineand 2 equivalents of salicylaldeyde.

We turn now to the second embodiment.

Preferably the cocatalyst is a salt where the cation is

and the anion is selected from the group consisting of Cl⁻ and OBzF₅ ⁻where OBzF₅ is 2,3,4,5,6-pentafluorobenzoate. [PPN][OBzF₅] is novel.

Catalyst systems used in reactions set forth in working examples are:catalyst system where the catalyst has the structural Formula (VIII)where X is OBzF₅ and the cocatalyst is [PPN]Cl; catalyst system wherethe catalyst has the structural Formula (VIII) where X is Cl and thecocatalyst is [PPN][OBzF₅]; catalyst system where the catalyst has thestructural formula (VIII) where X is Cl and the cocatalyst is [PPN]Cl;and catalyst system where the cocatalyst is NBu₄Cl and the catalyst hasthe structural formula (VIII) where X is OBzF₅.

The [PPN]carboxylate complexes can be prepared by reacting [PPN]X withthe appropriate sodium carboxylate.

We turn now to the third embodiment herein.

Preferably the CO₂ pressure ranges from 10 to 850 psi, the reactiontemperature ranges from 20 to 25° C., the reaction time ranges from 0.5to 4 hours, the catalyst has the structure (VIII) where X is Br, Cl orOBzF₅ and the alkylene oxide to catalyst ratio on a cobalt basis rangesfrom 400:1 to 600:1.

The alkylene oxide used herein can be, for example, rac-propylene oxide,or enantiomercially enriched-propylene oxide, e.g., S-propylene oxide orR-propylene oxide. Other epoxides such as butene oxide or cyclohexeneoxide can also be employed.

We turn now to the fourth embodiment herein.

In a preferred case, the catalyst has the structural formula (VIII)where X is Cl and the cocatalyst is [PPN][OBzF₅].

In the experiments carried out, the propylene oxide was rac-propyleneoxide.

We turn now to the fifth embodiment herein.

The polymers of the fifth embodiment can be made by the method of thefourth embodiment and working examples are set forth hereinafter.

We turn now to the sixth embodiment herein. The polymers of the sixthembodiment can be made by the methods of the third and fourthembodiments and working examples are set forth in Qin, Z., et al, Angew.Chem. Ind. Ed. 42, 5484-5487 (2003) and in working examples hereinafter.

The polymers of the fifth and sixth embodiments can be produced ascrystalline polymers. Crystalline polymers have the advantage that theyare mechanically strong and resist thermal deformation.

The polypropylene carbonates) produced herein can be converted topolyurethanes by reaction with polyacid, polyol or water to make apolypropylene carbonate) with two or more OR groups which in turn wouldbe reacted with a diisocyanate to prepare polyurethane.

The invention is illustrated in Qin, Z., et al., Angew. Chem. Int. Ed.42, 5484-5487 (2003) and in working examples below.

WORKING EXAMPLE I Synthesis of (VII) Where R is Br,[(R,R)-(salen-8)CoOAc]

First(R,R)—N,N′-bis(5-bromo-3-tert-butyl-salicylidene)-1,2-cyclohexanediamine,[(R,R)-(salen-8)H₂], was synthesized as follows:

Under an atmosphere of nitrogen, to an aqueous solution of(R,R)-1,2-diaminocyclohexane L-tartrate (1.321 g, 5.0 mmol) and K₂CO₃(1.382 g, 10.0 mmol) in water (10 mL) was added ethanol (50 mL). Themixture was heated to 80° C., and to it was dropwise added5-bromo-3-tert-butyl-2-hydroxybenzaldehyde, prepared by a modificationof the methods described in Cavazzini, M., et al., Eur. J. Org. Chem.(2001), 4639-4649 and Lam, F., et al., J. Org. Chem. 61, 8414-8418(1996) (2.571 g, 10.0 mmol) in THF (10 mL), resulting a yellow solution.After the mixture was stirred for 2 h and cooled down to roomtemperature, water (150 mL) was added to precipitate yellow crude titlecompound. The precipitate was redissolved in diethyl ether (100 mL) andwashed with brine (100 mL), water (100 mL), and dried over anhydrousNa₂SO₄, and then concentrated. A yellow crystalline product was obtainedafter recrystallization from ethanol. Yield: 2.60 g, 88%. ¹H NMR (CDCl₃,500 MHz) δ 13.80 (s, 2H), 8.18 (s, 2H), 7.31 (d, ⁴J=2.0 Hz, 2H), 7.09(d, ⁴J=2.0 Hz, 2H), 3.33 (br, 2H), 2.00 (br, 2H), 1.90 (br, 2H), 1.75(M, 2H), 1.47 (m, 2H), 1.38 (s, 18H), ¹³C NMR (CDCl₃, 125 MHz) δ 24.40,39.31, 159.57, 164.68, LRMS (EI) Cald. 592, found 592.

(R,R)—N,N′-bis(5-bromo-3-tert-butyl salicylidene)-1,2-diaminocyclohexane cobalt (II), [(R,R)-(salen-8)Co], was prepared as follows:

To a solution of the ligand [(R,R)-(salen-8)H₂](1.777 g, 3.0 mmol) intoluene (10 mL) under nitrogen was added a solution of Co(OAc)₂ (0.708g, 4 mmol) in MeOH (10 mL) via a cannula, affording a dark redprecipitate. The mixture was stirred at 80° C. for 2 h. After thereaction mixture was cooled down to room temperature and concentrated invacuo, the residue was dissolved in CH₂Cl₂ (50 mL) and passed through acelite pad to remove the excess Co(OAc)₂. Removing solvent of thefiltrate afforded a dark red powder. Yield: 1.85 g, 95%. The molecularstructure of this complex was determined by single crystal X-raydiffraction.

(R,R)—N,N′-bis(5-bromo-3-tert-butylsalicylidene)-1,2-diaminocyclohexanecobalt (III) acetate, [(R,R)-(salen-8)CoOAc] was prepared as follows:

To a solution of the [(R,R)-(salen-8)Co] (1.750 g, 2.70 mmol) in toluene(15 mL) and CH₂Cl₂ (50 mL) was added acetic acid (1.62 g, 27.0 mmol).The solution quickly changed from red to brown. After 2 h, all solventsand excess acetic acid were removed and the residue was dried toconstant weight under vacuum, quantitatively affording a brown powder.¹H NMR (CD₂Cl₂, 400 MHz) δ 7.52 (s, 1H), 7.43 (br, 2H), 7.34 (d, ⁴J=2.4Hz, 1H), 7.32 (d, ⁴J=2.4 Hz, 1H), 7.14 (s, 1H), 4.16 (m, 1H), 3.22 (M,1H), 2.81 (M. 1H), 2.74 (M, 1H), 2.00 (M, 2H), 1.96 (br, 1H), 1.89 (br,2H), 1.73 (M, 1H), 1.53 (s, 3H), 1.48 (s, 9H), 1.24 (s, 91-1).

WORKING EXAMPLE II Synthesis of (VII) Where R is H,[(R,R)-(salen-7)CoOAc]

(R,R)—N,N′-Bis(3-tert-butyl-salicylidene)-1,2-cyclohexanediamine,[(R,R)-(salen-7)H₂] was prepared as described in Pospisil, P. J., etal., Chem. Eur. J. 2, 974-980 (1996).

(R,R)—N,N′-bis(3-tert-butylsalicylidene)-1,2-diaminocyclohexane cobalt,[(R,R)-(salen-7)Co] was prepared from [(R,R)-(salen-7)H₂] by a similarprocedure to that used for [(salen-8)Co] in working Example I. The yieldwas 98%.

(R,R)—N,N′-bis(3-tert-butylsalicylidene)-1,2-diamino cycl ° hexanecobalt (III) acetate, [(R,R)-(salen-7)CoOAc] was prepared in similarfashion to [(R,R)-(salen-8)CoOAc] except only toluene was used assolvent. A dark brown powder was obtained quantitatively. ¹H NMR(CD₂Cl₂, 400 MHz) δ 7.60 (s, 1H), 7.42 (s, 1H), 7.28 (s, 2H), 7.20 (s,2H), 6.62 (s, 1H), 6.43 (s, 1H), 4.39 (s, 1H), 3.38 (s, 1H), 2.84 (br,2H), 1.77-2.20 (br M, 6H), 1.56 (br, 12H), 1.38 (s, 9H).

WORKING EXAMPLE III Synthesis of (VII) Where R is Su and (VIII) Where Xis OAc, [(R,R)-(salen-1)CoOAc]

(R,R)—N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexanecobalt (III) acetate, [(R,R)-(salen-1)CoOAc] is synthesized as describedin Schaus, S. E., et al., J. Am. Chem. 124, 1307-1315 (2002) andTokunaga, M., Science 277, 936-938 (1997). The material here waspurchased from Strem.

WORKING EXAMPLE IV Copolymerizations

Copolymerizations of propylene oxide (PO) and CO₂ were carried out asfollows using [(R,R)-(salen-8)CoOAc], the product of Working Example I,[(R,R)-(salen-7)CoOAc], the product of Working Example II,[(R,R)-(salen-1)CoOAc], the product of Working Example III, [Zn(BDI)OAc]prepared as described in Allen, S. D., et al., J. Am. Chem. Soc. 124,14284-14285 (2002), Reference [14], and [Cr(salph)Cl] prepared asdescribed in Darensbourg, D. J., et al., J. Am. Chem. Soc. 125,7586-7591 (2003), Reference [16]:

General PO/CO₂ copolymerization Procedure: A glass tube equipped with astir bar was charged with catalyst, and then was inserted into apre-dried 100 mL Parr autoclave. After the assembled autoclave wasevacuated under vacuum and refilled with nitrogen for three times, POwas added through a valve using a syringe. The autoclave was brought toappropriate temperature, and then pressurized to the appropriatepressure with CO₂. After the allotted reaction time, the unreacted POwas recovered using vacuum transfer and analyzed by a chiral GC. A smallamount of the residue was removed for ¹H NMR analysis. The crude polymerwas dissolved in CH₂Cl₂ (10-20 mL), and then a small amount of MeOH wasadded. The polymer was precipitated from diethyl ether, collected byfiltration and dried in vacuo to constant weight.

Conditions and results are set forth in Table 1 below.

TABLE 1 Carbonate Pressure Temp Time TOF^([b]) Selectivity LinkagesMn^([d]) PDI Entry^([a]) Catalyst Epoxide [PO]:[Cat] (psi) (° C.) (h)(h⁻¹) (% PPC)^([c]) (%)^([c]) (g/mol) (M_(w)/M_(n))  1 [(R,R)-(salen-rac-PO 500 800 25 3 81 >99 95 15 300 1.22 8)CoOAc]  2 [(R,R)-(salen-rac-PO 500 600 25 3 19 >99 94   3100 2.60 8)CoOAc]  3 [(R,R)-(salen-rac-PO 500 800 40 3 17 >99 90   5600 1.21 8)CoOAc]  4 [(R,R)-(salen-rac-PO 500 800 30 3 69 >99 94 12 200 1.26 8)CoOAc]  5 [(R,R)-(salen-rac-PO 500 800 20 3 42 >99 95   8000 1.44 8)CoOAc]  6 [(R,R)-(salen-rac-PO 500 800 15 3 31 >99 95   7600 1.51 8)CoOAc]  7 [(R,R)-(salen-rac-PO 200 800 25 3 51 >99 95   8200 1.25 8)CoOAc]  8 [(R,RHsalen-rac-PO 2000 800 25 8 38 >99 95 21 700 1.41 8)CoOAc]  9 [(R,R)-(salen-rac-PO 200 800 25 3 51 >99 96   6600 1.21 7)CoOAc] 10 [(R,R)-(salen-rac-PO 500 800 25 3 66 >99 96   9000 1.31 7)CoOAc] 11 [(R,R)-(salen-rac-PO 200 800 25 3 42 >99 99   5700 1.28 1)CoOAc] 12 [(R,R)-(salen-rac-PO 500 800 25 3 59 >99 99   8100 1.57 1)CoOAc] 13 [(R,R)-(salen-(S)-PO 500 800 25 3 71 >99 99   6900 1.58 1)CoOAc] 14^([e]) [Zn(BDI)OAc]rac-PO 2000 300 25 2 184 87 99 35 900 1.11 15^([f]) [Cr(salph)Cl] rac-PO1500 490 75 4 160 71 98 16 700 1.38 All of the polymerizations werecarried out in 3.5 mL of neat propylene oxide (PO). ^([b])Turnoverfrequency of PO to PPC. ^([c])Determined by using ¹H NMR spectroscopy.^([d])Determined by gel permeation chromatography in tetrahydrofuran at40° C., calibrated with polystyrene standards. ^([e])Reference [14].^([f])Reference [16].

As indicated by the percent selectivity (% PPC) for entries 1-13 ofTable 1, cyclic propylene carbonate was not formed.[(R,R)-(salen-1)CoOAc] was found to be highly regioselective with 80%head to tail linkages. In contrast, the catalysts[(R,R)-(salen-8)CoOAc], [(R,R)-(salen-7)CoOAc] and [Zn (BDI) OAc] gavetypical regioselectivities of 70, 75 and 60%, respectively.

Polymerization of (S)-propylene oxide with enantiomerically pure[(R,R)-(salen-1)CoOAc], entry 13 in Table 1, yielded isotactic (S)polymer with head-to-tail content of 93%.

WORKING EXAMPLE V Synthesis of (VIII) Where X is II[(R,R)-(salen-1)CoI]

(R,R)—N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexanecobalt [(R,R)-(salen-1)Co] was purchased from Aldrich and recrystallizedfrom methylene chloride and methanol.

(R,R)—N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexanecobalt (III) iodide, [(R,R)-(salen-1)CoI] is synthesized as described inNielsen, L. P. C.; Stevenson, C. P.; Blackmond, D. G.; Jacobsen, E. N.J. Am. Chem. Soc. 2004, 126, 1360-1362 with the substitution of NaI forNaCl. ¹H NMR (DMSO-d₆, 500 MHz): δ 1.32 (s, 18H) 1.63 (m, 2H), 1.76 (s,18H), 1.91 (m, 2H), 2.02 (m, 2H), 3.10 (m, 2H), 3.66 (m, 2H), 7.45 (d,⁴J=2.5 Hz, 2H), 7.50 (d, ⁴J=2.5 Hz, 2H), 7.83 (s, 2H). ¹³C NMR (DMSO-d₆,125 MHz): δ 24.23, 29.54, 30.36, 31.49, 33.47, 35.71, 69.22, 118.59,128.63, 129.16, 135.82, 141.74, 161.95, 164.49. Anal. Calcd forC₃₆H₅₂N₂O₂CoI: C, 59.18; H, 7.17; N, 3.83. Found: C, 59.14; H, 7.05; N,3.75.

WORKING EXAMPLE VI Synthesis of (VIII) Where X is Br[(R,R)-(salen-1)CoBr]

(R,R)—N,N′-bis(3,5-di-tert-butyl salicylidene)-1,2-diaminocyclohexanecobalt [(R,R)-(salen-1)Co] was purchased from Aldrich and recrystallizedfrom methylene chloride and methanol.

(R,R)—N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexanecobalt (III) bromide, [(R,R)-(salen-1)CoBr] is synthesized as describedin Nielsen, L. P. C.; Stevenson, C. P.; Blackmond, D. G.; Jacobsen, E.N. J. Am. Chem. Soc. 2004, 126, 1360-1362 with the substitution of NaBrfor NaCl. ¹H NMR (DMSO-d₆, 500 MHz): δ 1.30 (s, 18H), 1.58 (m, 2H), 1.74(s, 18H), 1.92 (m, 2H), 2.00 (m, 2H), 3.06 (m, 2H), 3.59 (m, 2H), 7.44(d, ⁴J=3.0 Hz, 2H), 7.47 (d, ⁴J=3.0 Hz, 2H), 7.83 (s, 2H). ¹³C NMR(DMSO-d₆, 125 MHz): δ 24.32, 29.57, 30.43, 31.55, 33.58, 35.82, 69.32,118.61, 128.78, 129.28, 135.87, 141.84, 162.11, 164.66. Anal. Calcd forC₃₆H₅₂N₂O₂CoBr: C, 63.25; H, 7.67; N, 4.10. Found: C, 63.05; H, 7.69; N,4.06.

WORKING EXAMPLE VII Synthesis of (VIII) Where X is Cl[(R,R)-(salen-1)CoCl]

(R,R)—N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexanecobalt (III) chloride, [(R,R)-(salen-1)CoCl] was prepared as previouslydescribed in Nielsen, L. P. C.; Stevenson, C. P.; Blackmond, D. G.;Jacobsen, E. N. J. Am. Chem. Soc. 2004, 126, 1360-1362. Additionalcharacterization: ¹³C NMR (DMSO-d₆, 125 MHz): δ 24.34, 29.51, 30.40,31.56, 33.51, 35.78, 69.27, 118.58, 128.78, 129.28, 135.86, 141.84,162.08, 164.68.

WORKING EXAMPLE VIII Synthesis of (VIII) where X isOBzF₅-[(R,R)-(salen-1)CoOBzF₅]

(R,R)—N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexanecobalt [(R,R)-(salen-1)Co] was purchased from Aldrich and recrystallizedfrom methylene chloride and methanol.

[(R,R)-(salen-1)Co] (1.2 g, 2.0 mmol) and pentafluorobenzoic acid (0.42g, 2.0 mmol) were added to a 50 mL round-bottomed flask charged with aTeflon stir bar. Toluene (20 mL) was added to the reaction mixture, andit was stirred open to air at 22° C. for 12 h. The solvent was removedby rotary evaporation at 22° C., and the solid was suspended in 200 mLof pentane and filtered. The dark green crude material was dried invacuo and collected in quantitative yield. ¹H NMR (DMSO-d₆, 500 MHz): δ1.30 (s, 18H), 1.59 (m, 2H), 1.74 (s, 18H), 1.90 (m, 2H), 2.00 (m, 2H),3.07 (m, 2H), 3.60 (m, 2H), 7.44 (d, ⁴J=2.5 Hz, 2H), 7.47 (d, ⁴J=3.0 Hz,2H), 7.81 (s, 2H). ¹³C NMR (DMSO-d₆, 125 MHz): δ 24.39, 29.61, 30.13,30.42, 31.55, 33.57, 35.83, 69.38, 118.59, 128.78, 129.29, 135.86,141.83, 162.21, 164.66. Carbons on the phenyl group ofpentafluorobenzoate were not assigned in the ¹³C NMR spectrum owing tocomplex carbon fluorine splitting patterns. ¹⁹F NMR (470 MHz, DMSO-d₆):δ −163.32 (m), −162.50 (m), −144.48 (m). Anal. Calcd forC₄₃H₅₂O₄N₂F₅Co.H₂O: C, 62.01; H, 6.54; N, 3.36. Found: C, 62.25; H,6.38; N, 3.42.

WORKING EXAMPLE IX Synthesis of (IX) Where R¹¹ is ^(t)Bu and R¹⁰ is H[(R,R)-(salen-7)CoBr]

(R,R)—N,N′-bis(3-tert-butylsalicylidene)-1,2-diaminocyclohexane cobalt[(R,R)-(salen-7)Co] is synthesized as described in Sun, W.; Xia, C.-G.;Zhao, P.-Q. J Mol Catal A: Chem 2002, 184, 51.

(R,R)—N,N′-bis(3-tert-butylsalicylidene)-1,2-diaminocyclohexane cobalt(III) bromide [(R,R)-(salen-7)CoBr] was prepared as follows:[(R,R)-(Salen-7)Co] (470 mg, 0.96 mmol) and p-toluenesulfonic acidmonohydrate (190 mg, 1.0 mmol) were added to a 50 mL round-bottomedflask with a Teflon stir bar, and 10 mL of methylene chloride was added.The mixture was stirred open to air for 1 h at 22° C., and the methylenechloride was removed in vacuo. The solid was suspended in pentane andfiltered to afford the intermediate [(R,R)-(salen-7)CoOTs](OTs=tosylate). This solid was dissolved in 25 mL of methylene chlorideand added to a 100 mL separatory funnel. The organic layer was rinsedwith saturated aqueous NaBr (3×25 mL). The organic layer was dried overNa₂SO₄, filtered and dried in vacuo. The crude material was suspended inpentane and filtered to afford the solid [(R,R)-(salen-7)CoBr] (210 mg,38%). ¹H NMR (DMSO-d₆, 500 MHz): δ 1.59 (m, 2H), 1.73 (s, 18H), 1.90 (m,2H), 2.01 (m, 2H), 3.06 (m, 2H), 3.60 (m, 2H), 6.59 (t, ³J=7.0 Hz, 2H),7.38 (d, ³J=7.0 Hz, 2H), 7.49 (d, ³J=7.0 Hz, 2H), 7.87 (s, 2H). ¹³C NMR(DMSO-d₆, 125 MHz): δ 24.18, 29.49, 30.31, 35.62, 69.33, 114.47, 119.19,131.17, 133.83, 142.49, 164.19, 164.37.

WORKING EXAMPLE X Synthesis of (IX) Where R¹¹ is ^(t)Bu and R¹⁰ is Br[(R,R)-(salen-8)CoBr]

The procedure for the synthesis of [(R,R)-(salen-7)CoBr] was applied tothe synthesis of (R,R)—N,N′-bis(5-bromo-3-tert-butylsalicylidene)-1,2-diamino cyclohexane cobalt (III) bromide (R,R)-(salen-8)CoBr; however,[(R,R)-(salen-8)Co] (synthesis described above) (360 mg, 0.56 mmol) andp-toluenesulfonic acid monohydrate (110 mg, 0.60 mmol) were stirred for12 h in methylene chloride (10 mL). Following the salt metathesis withNaBr, the product (R,R)-(salen-8)CoBr was obtained (180 mg, 44%). ¹H NMR(DMSO-d₆, 500 MHz): δ 1.59 (m, 2H), 1.71 (s, 18H), 1.88 (m, 2H), 2.00(m, 2H), 3.04 (m, 2H), 3.61 (m, 2H), 7.37 (d, ⁴J=2.5 Hz, 2H), 7.80 (d,⁴J=2.5 Hz, 2H), 7.96 (s, 21-1). ¹³C NMR (DMSO-d₆, 125 MHz): δ 24.06,29.51, 29.85, 35.78, 69.55, 104.97, 120.73, 133.45, 135.04, 145.16,163.19, 164.22.

WORKING EXAMPLE XI Synthesis of (IX) Where R¹¹ is Me and R¹⁰ is H[(R,R)-(salen-10)CoBr]

(R,R)—N,N′-Bis(3-methylsalicylidene)-1,2-diaminocyclohexane cobalt[(R,R)-(salen-10)Co] is synthesized as described in Szlyk, E.;Surdykowski, A.; Barwiolek, M.; Larsen, E. Polyhedron 2002, 21, 2711.

The procedure for the synthesis of [(R,R)-(salen-7)CoBr] was applied tothe synthesis of(R,R)—N,N′-bis(3-methylsalicylidene)-1,2-diaminocyclohexane cobalt (III)bromide [(R,R)-(salen-10)CoBr], however; [(R,R)-(salen-10)Co](210 mg,0.52 mmol) and p-toluenesulfonic acid monohydrate (100 mg, 0.53 mmol)were stirred for 2 h in methylene chloride (20 mL). An excess ofmethylene chloride (200 mL) was used in the salt metathesis with NaBr inorder to dissolve all of the [(R,R)-(salen-10)CoOTs] intermediate.Following this reaction, the product [(R,R)-(salen-10)CoBr] was obtained(170 mg, 67%). NMR (DMSO-d₆, 500 MHz): δ 1.57 (m, 2H), 1.86 (m, 2H),1.99 (m, 2H), 2.64 (s, 6H), 3.05 (m, 2H), 3.63 (m, 2H), 6.58 (t, ³J=7.0Hz, 2H), 7.31 (d, ³J=7.0 Hz, 2H), 7.48 (d, ³J=7.0 Hz, 2H), 8.02 (s, 2H).¹³C NMR (DMSO-d₆, 125 MHz): δ 17.12, 24.17, 29.45, 69.60, 114.57,117.89, 130.68, 132.86, 134.36, 163.32, 164.13.

WORKING EXAMPLE XII Synthesis of (IX) Where R¹¹ is CPh (CH₃)₂ and R¹⁰ isCPh (CH₃)₂ [(R,R)-(salen-11)CoBr]

3,5-Bis(α,α′-dimethylbenzyl)-2-hydroxybenzaldehyde was synthesized asdescribed in A. E. Cheman, E. B. Lobkovsky and G. W. Coates,Macromolecules, 2005, 38, 6259-6268.

Synthesis of(R,R)—N,N′-bis(3,5-bis(α,α′-dimethylbenzyl)salicylidene)-1,2-diaminocyclohexane,[(R,R)-(salen-11)H₂]: (R,R)-1,2-Diaminocyclohexane-L-tartrate (0.74 g,2.8 mmol) and K₂CO₃ (0.77 g, 5.6 mmol) were stirred in H₂O (8 mL) untilall was dissolved. To it was added a solution of3,5-bis(α,α′-dimethylbenzyl)-2-hydroxybenzaldehyde (2.0 g, 5.6 mmol) inethyl alcohol (35 mL) and the mixture was refluxed for 3 h. The reactionmixture was then cooled to 22° C., filtered, and washed thoroughly withH₂O and then with cold ethyl alcohol. The crude yellow solid was driedand collected (1.8 g, 81%). ¹H NMR (CDCl₃, 500 MHz): δ 1.29 (m, 2H),1.52 (m, 2H), 1.59 (s, 6H), 1.67 (s, 12H), 1.68 (s, 6H), 1.73 (m, 4H),3.11 (m, 2H), 6.94 (d, ⁴J=2.5 Hz, 2H), 7.16 (it, ³J=7.0 Hz, ⁴J=1.5 Hz,2H), 7.16-7.29 (m, 20H), 8.08 (s, 2H), 13.21 (broad s, 2H). ¹³C NMR(CDCl₃, 125 MHz): δ 24.31, 28.71, 30.38, 30.95, 31.04, 33.22, 42.25,42.44, 72.25, 118.01, 125.11, 125.68, 125.70, 126.78, 127.74, 127.92,128.11, 129.27, 135.82, 139.46, 150.64, 150.76, 157.77, 165.38. HRMS(ESI) m/z calcd (C₅₆H₆₂N₂O₂+H⁺) 795.4890, found 795.4900.

Synthesis of(R,R)—N,N′-bis(3,5-bis(α,α′-dimethylbenzyl)salicylidene)-1,2-diaminocyclohexanecobalt, [(R,R)-(salen-11)Co]: [(R,R)-(salen-11)H₂] (0.69 g, 0.87 mmol)and cobalt acetate tetrahydrate (0.26 g, 1.0 mmol) were added to aSchlenk flask charged with a Teflon stir bar under N₂. A 1:1 mixture oftoluene and methanol (30 mL); (degassed for 20 min by sparging with dryN₂) was added and stirred at 22° C. for 2 h. The resultant redprecipitate was filtered in air and washed with distilled water (50 mL)and methanol (50 mL) and collected as a crude solid (0.59 g, 80%). JR(KBr, 766, 809, 1034, 1105, 1246, 1325, 1340, 1362, 1459, 1528, 1605,2872, 2937, 2968, 3026, 3061, 3453. HRMS (ESI) m/z calcd (C₅₆H₆₀CoN₂O₂)851.3987, found 851.3972.

Synthesis of(R,R)—N,N′-bis(3,5-bis(α,α′-dimethylbenzyl)salicylidene)-1,2-diaminocyclohexanecobalt (III) bromide, [(R,R)-(salen-11)CoBr]: [(R,R)-(salen-11)Co] (0.50g, 0.59 mmol) and p-toluenesulfonic acid monohydrate (0.11 g, 0.59 mmol)were added to a 50 mL round bottomed flask charged with a Teflon stirbar. Methylene chloride (10 mL) was added to the reaction mixture andstirred for 2 h open to air at 22° C. The solvent was removed by rotaryevaporation at 22° C., and the crude solid was washed with pentane (100mL) and filtered. The crude material was dissolved in methylene chloride(25 mL) and added to a 125 mL separatory funnel. The organic layer wasrinsed with saturated aqueous NaBr (3×25 mL). The organic layer wasdried over Na₂SO₄ and evaporated under reduced pressure. The solid waswashed with pentane (100 mL) and filtered to afford[(R,R)-(salen-11)CoBr] (0.16 g, 29%).

WORKING EXAMPLE XIII Synthesis of (X)—[(salen-6)CoBr]

N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminophenylene cobalt,[(salen-6)Co] is synthesized as described in H. Shimakoshi, H. Takemoto,I. Aritome and Y. Hisaeda, Tetrahedron Lett., 2002, 43, 4809-4812.

Employing the same reaction conditions as for [(R,R)-(salen-11)CoBr],[(salen-6)Co] (1.0 g, 1.7 mmol) and p-toluenesulfonic acid monohydrate(0.32 g, 1.7 mmol) were used to produceN,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminophenylene cobalt(III) bromide, [(salen-6)CoBr] (0.35 g, 30%). ¹H NMR (DMSO-d₆, 500 MHz):δ 1.35 (s, 18H), 1.78 (s, 18H), 7.55 (d, ⁴J=2.5 Hz, 2H), 7.56 (td,³J=6.5 Hz, ⁴J=3.5 Hz, 2H), 7.66 (d, ⁴J=2.5 Hz, 2H), 8.63 (dd, ³J=6.5 Hz,⁴J=3.5 Hz, 2H), 8.95 (s, 2H). ¹³C NMR (DMSO-d₆, 125 MHz): δ 30.34,31.34, 33.79, 36.01, 117.40, 117.45, 128.14, 129.97, 131.00, 136.59,142.07, 144.72, 161.60, 165.59. HRMS (EI) m/z calcd (C₃₆H₄₆BrCoN₂O₂—Br)597.2891, found 597.2878.

WORKING EXAMPLE XIV Synthesis of (XI) Where R⁷ is Me, R⁸ is H and R⁹ isH [(R)-(salen-2)CoBr]

(R)—N,N′-bis(3,5-di-tert-butyl salicylidene)-1,2-diaminopropane[(R)-(salen-2)H₂] was synthesized as described in D. J. Darensbourg, R.M. Mackiewicz, J. L. Rodgers, C. C. Fang, D. R. Billodeaux and J. H.Reibenspies, Inorg. Chem., 2004, 43, 6024-6034.

(R)—N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminopropane cobalt[(R)-(salen-2)Co] was synthesized as follows: Employing the samereaction conditions as for [R,R)-(salen-11)Co], [(R)-(salen-2)H₂] (2.8g, 5.5 mmol) and cobalt acetate tetrahydrate (1.7 g, 6.8 mmol) in a 1:1mixture of degassed toluene and methanol (150 mL) were used to afford acrude red solid (2.9 g, 95%). IR (KBr, cm⁻¹): 787, 837, 874, 1179, 1204,1255, 1320, 1361, 1385, 1466, 1528, 1596, 2871, 2909, 2956. HRMS (ESI)m/z calcd (C₃₃H₄₈CoN₂O₂) 563.3048, found 563.3046.

(R)—N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminopropane cobalt(III) bromide [(R)-(salen-2)CoBr] was synthesized as follows:[(R)-(salen-2)Co] (1.0 g, 1.8 mmol) and p-toluenesulfonic acidmonohydrate (0.34 g, 1.8 mmol) were added to a 50 mL round-bottomedflask charged with a Teflon stir bar. Methylene chloride (30 mL) wasadded to the reaction mixture and stirred for 2 h open to air at 22° C.The solvent was removed by rotary evaporation at 22° C., and the crudedark green solid was dissolved in pentane (50 mL) and filtered. Thesolvent was removed by rotary evaporation, and the material wasdissolved in methylene chloride (50 mL) and added to a 250 mL separatoryfunnel. The organic layer was shaken vigorously with saturated aqueousNaBr (3×50 mL). The organic layer was dried over Na₂SO₄ and evaporatedunder reduced pressure. The solid was suspended in pentane and filteredto afford a crude black solid (0.50 g, 43%). ¹H NMR (DMSO-d₆, 500 MHz):δ 1.30 (s, 18H), 1.61 (d, ³J=6.5 Hz, 3H), 1.73 (s, 18H), 3.86 (m, 1H),4.21 (m, 1H), 4.32 (m, 1H), 7.33 (d, ⁴J=2.0 Hz, 1H), 7.40 (d, ⁴J=2.0 Hz,1H), 7.44 (s, 1H), 7.45 (s, 1H), 7.93 (s, 1H), 8.09 (s, 1H). ¹³C NMR(DMSO-d₆, 125 MHz): δ 18.45, 30.34, 30.38, 31.51, 31.54, 33.39, 33.43,35.71, 35.73, 62.99, 64.57, 118.57, 118.88, 128.15, 128.67, 128.74,128.82, 135.84, 136.01, 141.73, 142.01, 161.67, 161.94, 167.03, 168.55.HRMS (EI) m/z calcd. (C₃₃H₄₈BrCoN₂O₂—Br) 563.3048, found 563.3037.

WORKING EXAMPLE XV Synthesis of (XI) Where R⁷, R⁸ and R⁹ are H[(salen-3)CoBr]

N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminoethane cobalt[(salen-3)Co] was synthesized as described in B. Rhodes, S. Rowling, P.Tidswell, S. Woodward and S. M. Brown, J Mol Catal A: Chem, 1997, 116,375-384.

Synthesis of N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminoethanecobalt (III) bromide [(salen-3)CoBr]: Employing the same reactionconditions as for [(R,R)-(salen-2)CoBr], [(salen-3)Co] (0.30 g, 0.55mmol) and p-toluenesulfonic acid monohydrate (0.10 g, 0.55 mmol) wereused. Following the salt metathesis with NaBr, the crude product[(salen-5)CoBr] was obtained (86 mg, 25%). ¹H NMR (DMSO-d₆, 500 MHz): δ1.30 (s, 18H), 1.73 (s, 18H), 4.14 (s, 4H), 7.31 (d, ⁴J=3.0 Hz, 2H),7.45 (d, ⁴J=3.0 Hz, 2H), 8.12 (s, 2H). ¹³C NMR (DMSO-d₆, 125 MHz): δ30.36, 31.52, 33.43, 35.77, 58.24, 118.51, 128.27, 128.74, 135.93,142.05, 162.13, 168.65. HRMS (ED m/z calcd (C₃₂H₄₆BrCoN₂O₂—Br) 549.2891,found 549.2885.

WORKING EXAMPLE XVI Synthesis of (XI) Where R⁷ is Me, R⁸ is Me and R⁹ isH [(salen-4)CoBr]

Synthesis ofN,N′-bis(3,5-di-tert-butylsalicylidene)-2-methyl-1,2-diaminopropane[(salen-4)H₂]: To a solution of 3,5-di-tert-butyl-2-hydroxybenzaldehyde(3.0 g, 13 mmol) in ethyl alcohol (60 mL) was added2-methyl-1,2-propanediamine (0.67 mL, 6.4 mmol) and the mixture wasrefluxed for 3 h. The reaction was cooled to 22° C., and the solvent wasremoved in vacuo. The crude yellow solid was recrystallized from ethylalcohol at −20° C. affording yellow needles (3.1 g, 93%). ¹H NMR (CDCl₃,500 MHz): δ 1.28 (s, 9H), 1.29 (s, 9H), 1.43 (s, 24H), 3.71 (s, 2H),7.07 (d, ⁴J=4.5 Hz, 1H), 7.09 (d, ⁴J=4.5 Hz, 1H), 7.35 (d, ⁴J=4.5 Hz,1H), 7.36 (d, ⁴, J=4.5 Hz, 1H), 8.35 (s, 1H), 8.39 (s, 1H) 13.67 (s,1H), 14.21 (s, 1H). ¹³C NMR (CDCl₃, 125 MHz): δ 25.73, 29.60, 29.63,31.63, 31.66, 34.26, 35.17, 35.19, 60.14, 70.71, 117.99, 118.08, 126.22,126.35, 126.90, 127.18, 136.78, 136.80, 139.98, 140.12, 158.32, 158.52,162.88, 167.78. HRMS (ESI) m/z calcd (C₃₄H₅₂N₂O₂+H⁺) 521.4107, found521.4110.

Synthesis ofN,N′-bis(3,5-di-tert-butylsalicylidene)-2-methyl-1,2-diaminopropanecobalt [(Salen-4)Co]: [(Salen-4)H₂] (2.3 g, 4.4 mmol) and cobalt acetatetetrahydrate (1.3 g, 5.2 mmol) were added to a Schlenk flask chargedwith a Teflon stir bar under N₂. A 1:1 mixture of toluene and methanol(100 mL); (degassed for 20 min by sparging with dry N₂) was added andstirred at 22° C. for 2 h. The resultant red precipitate was filtered inair and washed with distilled water (50 mL) and methanol (50 mL) andcollected as a crude solid (2.3 g, 90% yield). IR (KBr, cm⁻¹): 786, 842,871, 1178, 1255, 1318, 1363, 1390, 1464, 1528, 1595, 2870, 2909, 2959.HRMS (ESI) m/z calcd (C₃₄H₅₀CoN₂O₂) 577.3204, found 577.3226.

Synthesis ofN,N′-bis(3,5-di-tert-butylsalicylidene)-2-methyl-1,2-diaminopropanecobalt (III) bromide [(salen-4)CoBr]: [(salen-4)Co] (0.30 g, 0.52 mmol)and p-toluenesulfonic acid monohydrate (99 mg, 0.52 mmol) were added toa 50 mL round-bottomed flask charged with a Teflon stir bar. Methylenechloride (30 mL) was added to the reaction mixture and stirred for 2 hopen to air at 22° C. The solvent was removed by rotary evaporation at22° C., and the crude dark green solid was dissolved in pentane (50 mL)and filtered. The solvent was removed by rotary evaporation, and thematerial was dissolved in methylene chloride (50 mL) and added to a 250mL separatory funnel. The organic layer was shaken vigorously withsaturated aqueous NaBr (3×50 mL). The organic layer was dried overNa₂SO₄ and evaporated under reduced pressure. The solid was suspended inpentane and filtered to afford a crude black solid (92 mg, 27%). NMR(DMSO-d₆, 500 MHz): δ 1.30 (s, 9H), 1.32 (s, 9H), 1.63 (s, 6H), 1.73 (s,9H), 1.74 (s, 9H), 4.02 (s, 2H), 7.36 (d, ⁴J=2.5 Hz, 1H), 7.45 (d,⁴J=2.5 Hz, 1H), 7.475 (s, 1H), 7.482 (s, 1H), 7.88 (s, 1H), 8.03 (s,1H). ¹³C NMR (DMSO-d₆, 125 MHz): δ 27.10, 30.35, 31.28, 31.32, 31.55,31.61, 33.43, 33.50, 35.72, 35.77, 66.98, 70.93, 118.36, 119.57, 128.05,128.75, 128.98, 129.35, 135.85, 136.41, 141.42, 142.12, 161.11, 161.96,166.31, 168.37. HRMS (EI) m/z calcd (C₃₄H₅₀BrCoN₂O₂—Br) 577.3204, found577.3199.

WORKING EXAMPLE XVII Synthesis of (XI) Where R⁷ is Ph, R⁸ is H and R⁹ isPh, [(R,R)-(salen-5)CoBr]

The synthesis of(R,R)—N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diphenylethylenediaminocobalt (II) [(R,R)-(salen-5)Co] is described in T. Fukuda and T.Katsuki, Tetrahedron, 1997, 53, 7201-7208.

Synthesis of(R,R)—N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diphenylethylenediaminocobalt (III) bromide [(R,R)-(salen-5)CoBr]: [(R,R)-(salen-5)Co] (0.25 g,0.36 mmol) and p-toluenesulfonic acid monohydrate (68 mg, 0.36 mmol)were added to a 50 mL round bottomed flask charged with a Teflon stirbar. Methylene chloride (10 mL) was added to the reaction mixture andstirred for 2 h open to air at 22° C. The solvent was removed by rotaryevaporation at 22° C., and the crude solid was washed with pentane (100mL) and filtered. The crude material was dissolved in methylene chloride(25 mL) and added to a 125 mL separatory funnel. The organic layer wasrinsed with saturated aqueous NaBr (3×25 mL). The organic layer wasdried over Na₂SO₄ and evaporated under reduced pressure. The solid waswashed with pentane (100 mL) and filtered to afford (R,R)-(salen-5)CoBr(0.12 g, 43%). ¹H NMR (DMSO-d₆, 500 MHz): δ 1.22 (s, 18H), 1.76 (s,18H), 5.62 (s, 2H), 6.97 (s, 2H), 7.23 (s, 2H), 7.41-7.48 (m, 12H). ¹³CNMR (DMSO-d₆, 125 MHz): δ 30.37, 31.35, 33.31, 35.73, 76.61, 117.64,128.48, 129.18, 129.90, 134.93, 136.07, 142.02, 162.31, 166.50. HRMS(EI) m/z calcd. (C₄₄H₅₄BrCoN₂O₂—Br) 701.3517 found 701.3502.

WORKING EXAMPLE XVII Application of [PPN]Cl, [PPh₄]Cl, [PPh₄Br],[NBu₄Cl]

Bis(triphenylphosphine)iminium chloride ([PPN]Cl),tetraphenylphosphonium chloride [PPh₄Cl], tetraphenylphosphoniumchloride [PPh₄Cl] were purchased from commercial sources andrecrystallized from dry methylene chloride and diethyl ether undernitrogen before use. Tetrabutylamonium chloride [NBu₄]Cl was purchasedfrom commercial sources and used as received. The synthesis ofbis(triphenylphosphine)iminium tetraphenyl borate [PPN][BPh₄] isdescribed in Reibenspies, J. H. Z. Kristallogr. 1994, 209, 620-621.Prakash, H.; Sisler, H. H. Inorg. Chem. 1968, 7, 2200-2203.

WORKING EXAMPLE XIX Synthesis of [PPN][OBzF₅]

Synthesis of bis(triphenylphosphine)iminium pentafluorobenzoate([PPN][OBzF₅]): NaOH (0.19 g, 4.7 mmol) and pentafluorobenzoic acid (1.0g, 4.7 mmol) were added to a 50 mL round-bottomed flask charged with aTeflon stir bar. Distilled H₂O (20 mL) was added to the reactionmixture, and it was stirred until all was dissolved. The solution wasadded to a 250 mL separatory funnel along with [PPN]Cl (0.40 g, 0.70mmol) and methylene chloride (40 mL), and the mixture was shakenvigorously for 10 min. The organic layer was collected and dried byrotary evaporation to yield crude [PPN][OBzF₅] in quantitative yield.Precipitation from dry methylene chloride and diethyl ether under N₂ at−20° C. afforded a white powder (0.35 g, 67%). ¹H NMR (CDCl₃, 500 MHz):δ 7.39-7.46 (m, 24H), 7.60-7.63 (m, 6H). ¹³C NMR (CDCl₃, 125 MHz):6116.93, 126.91 (dd, ¹J_(P-C)=108.0 Hz, ³J_(P-C)=1.5 Hz), 129.55 (m),132.02 (m), 133.88, 137.07 (d of m, ¹J_(F-C)=255.5 Hz), 139.92 (d of m,¹J_(F-C)=250.3 Hz), 143.24 (d of m, ¹J_(F-C)=247.3 Hz), 161.21. ¹⁹F NMR(470 MHz, CDCl₃): δ-164.64 (m), −159.92 (broad s), −142.52 (m). Anal.Calcd for C₄₃H₃₀F₅NO₂P₂: C, 68.89; H, 4.03; N, 1.87. Found: C, 69.07; H,3.95; N, 1.83.

WORKING EXAMPLE XX Copolymers Made Using [(R,R)-(salen-1)CoI] and[(R,R)-(salen-1)CoOAc]

Copolymerizations were carried out with conditions and results set forthin Table 2 below:

TABLE 2 Theoretical Reaction Time Yield^(b) TOF^(c) M_(n) ^(d) M_(n)^(e) Head-to-Tail Entry Complex Conditions (h) (%) (h⁻¹) (kg/mol)(kg/mol) M_(w)/M_(n) ^(e) Linkages^(f) (%) 1 [(R,R)-(salen-1)CoI]air-free 5 43 43 21.9 19.6 1.15 79 2 (R,R-(salen-1)CoI ambient 5 37 3718.9 9.5 1.33 81 3 (R,R)-(salen- air-free 2 30 74 15.1 15.5 1.16 831)CoOAc 4 (R,R)-(salen- ambient 2 25 62 12.7 10.4 1.31 83 1)CoOAc^(a)Polymerizations run in neat rac-propylene oxide (PO) with [PO]/[Co]= 500:1 at 22° C. with 800 psi of CO₂. Selectivity for poly(propylenecarbonate) (PPC) over propylene carbonate was >99% in all cases. Allproduct PPC contains ≧96% carbonate linkages as determined by ¹H NMRspectroscopy. ^(b)Based on isolated polymer yield. ^(c)Turnoverfrequency (TOF) = mol PO · mol Co⁻¹ · h⁻¹. ^(d)Theoretical numberaverage molecular weight (Mn) = TOF · h · 102 g/mol. ^(e)Determined bygel permeation chromatography calibrated with polystyrene standards inTHF. ^(f)Determined by ¹³C NMR spectroscopy.

As shown in Table 2, the runs in an inert atmosphere (entries 1 and 3)gave higher M_(n), and lower PDI than the same reactions carried out inair (entries 2 and 4).

WORKING EXAMPLE XXI Copolymerizations Using [(R,R)-(salen-1)CoI],[(R,R)-(salen-1)CoBr], [(R,R)-(salen-1)CoCl], [(R,R)-(salen-1)CoOAc] and[(R,R)-(salen-1)CoOBzF₅]

Copolymerizations were carried out with conditions and results set forthin Table 3 below:

TABLE 3 Yield^(b) TOF^(c) M_(n) ^(d) Head-to-Tail Entry Complex (%)(h⁻¹) (kg/mol) M_(w)/M_(n) ^(d) Linkages^(e) (%) 1[(R,R)-(salen-1)CoOAc] 30 75 15.5 1.16 83 2 [(R,R)-(salen-1)CoBzF₅] 3280 14.1 1.22 82 3 [(R,R)-(salen-1)CoCl] 26 65 13.4 1.19 82 4[(R,R)-(salen-1)CoBr] 36 90 21.0 1.14 82 5 [(R,R)-(salen-1)CoI] 13 3210.4 1.17 85 6 [(R,R)-(salen-1)CoI] + 28 70 16.2 1.24 81[(R,R)-(salen-1)CoBr] (50:1) ^(a)Polymerizations run in neatrac-propylene oxide (PO) with [PO]/[Co] = 500:1 at 22° C. with 800 psiof CO₂ for 2 h. Selectivity for poly(propylene carbonate) (PPC) overpropylene carbonate was >99% in all cases. All product PPC contains ≧92%carbonate linkages as determined by ¹H NMR spectroscopy. ^(b)Based onisolated polymer yield. ^(c)Turnover frequency (TOF) = mol PO · mol Co⁻¹· h⁻¹. ^(d)Determined by gel permeation chromatography calibrated withpolystyrene standards in THF. ^(e)Determined by ¹³C NMR spectroscopy.[OBzF₅] = pentafluorobenzoate.

As shown in Table 3, all the initiating groups tested, gave highmolecular weight polycarbonate with narrow molecular weightdistributions. Complex [(R,R)-(salen-1)CoI] provided the lowest TOFwhereas complex [(R,R)-(salen-1)CoBr] provided the highest TOF.

WORKING EXAMPLE XXII Using [(R,R)-(salen-1)CoBr] and Varying ReactionConditions

Copolymerizations were carried out with conditions and results set forthin Table 4 below:

TABLE 4 carbonate time yield TOF^(b) selectivity^(c) linkages^(c) M_(n)^(d) head to tail^(e) entry (h) (%) (h⁻¹) (% PPC) (%) (kg/mol) PDI (%) 11 20% 99 >99:1 98% 12.6 1.07 82% 2 2 36% 89 >99:1 97% 21.0 1.14 82% 3 338% 62 >99:1 97% 20.2 1.15 81% 4^(f) 8 19% 47 >99:1 97% 16.6 1.18 81%5^(g) 10 12% 6 >99:1 91% 7.2 1.15 85% 6^(h) 2 49% 121 >99:1 20.1 1.21Reaction conditions: 800 psi CO₂, 22° C., 1 mL of near rac-PO, [PO]/[Co]= 500. ^(b)Turnover frequency = (mol PO/(mol Zn · h)). ^(c)Determined by¹H NMR spectroscopy. ^(d)Determined by gel permeation chromatography intetrahydrofuran at 40° C. relative to polystyrene standards.^(e)Determined by ¹³C NMR spectroscopy. ^(f)[PO]/[Co] = 2000. ^(g)0° C.^(h)S-PO was used instead of rac-PO.

As shown in Table 4, increasing the time of polymerization increasesmolecular weight while slightly decreasing activities (entries 1-3)while more dilute reaction conditions decrease the catalyst activity(entry 4) as does lowering the reaction temperature to 0° C. (entry 5).As indicated by comparison of entries 2 and 6, the activity is enhancedif enantiomerically pure S—PO is used instead of racemic PO.

WORKING EXAMPLE XXIII

Effect of Change of Catalyst Backbone on Copolymerizations

Copolymerizations were carried out with conditions and results set forthin Table 5 below:

TABLE 5 Yield TOF Carbonate M_(n) Head-to-Tail Entry Catalyst (%)^(b)(h⁻¹)^(c) Linkages (%)^(d) (kg/mol)^(e) M_(w)/M_(n) ^(e) Linkages(%)^(f)  1 [(R,R)-(salen-1)CoBr] 38 63 97 20.2 1.15 81  2[CK)-(salen-2)CoBr] 32 53 97 13.9 1.18 82  3 [(salen-3)CoBr] 0 0 NA NANA NA  4 [(salen-4)CoBr] 38 63 >99 21.1 1.16 85  5 [(R,R)-(salen-5)CoBr]12 20 99 10.1 1.14 76  6 [(salen-6)CoBr] 14 23 89 11.3 1.29 79  7[(R,R)-(salen-7)CoBr] 33 55 96 15.2 1.13 76  8 [(R,R)-(salen-8)CoBr] 4372 94 35.8 1.15 70  9 [(R,R)-(salen-9)CoBr] 0 0 NA NA NA NA 10[(R,R)-(salen-10)CoBr] 8 13 69 4.5 1.12 80 11 [(R,R)-(salen-11)CoBr] 1118 >99 9.1 1.13 89 ^(a)Copolymerizations were run in neat rac-propyleneoxide (PO) with [PO]:[Co] = 500:1 at 22° C. with 800 psi of CO₂ for 3 h.Selectivity for poly(propylene carbonate) (PPC) over propylene carbonatewas >99:1 for entries 1-10, and 97:3 for entry 11. ^(b)Based on isolatedPPC yield. ^(c)Turnover frequency for PPC (mol PO · (mol Co)⁻¹ · h⁻¹).^(d)Determined by ¹H NMR spectroscopy. ^(e)Determined by GPC.^(f)Determined by ¹³C NMR spectroscopy.

Entries 1 and 4 produced the best results.

WORKING EXAMPLE XXIV Effect of Different Relative Levels of PPNClCo-catalyst on Copolymerization Results

Copolymerizations were carried out with variations and results as setforth in Tables 6 and 7 below:

TABLE 6 Yield^(b) TOF^(c) Selectivity^(d) M_(n) ^(e) Head-to-Tail EntryComplex (%) (h⁻¹) (% PPC) (kg/mol) M_(w)/M_(n) ^(e) Linkages^(f) (%) 1[(R,R)-(salen-1)CoOAc] 11 110 86 7.9 1.15 93 2 [(R,R)-(salen-1)CoOBzF₅]52 520 >99 43.0 1.10 93 3 [(R,R)-(salen-1)CoCl] 43 430 >99 35.4 1.09 954 [(R,R)-(salen-1)CoBr] 46 460 89 33.2 1.09 95 ^(a)Polymerizations runin neat rac-propylene oxide (PO) with [PO]:[[PPN]Cl]:[Co] = 2000:1:1 at22° C. with 200 psi of CO₂ for 2 h. All product poly(propylenecarbonate) (PPC) contains ≧98% carbonate linkages as determined by ¹HNMR spectroscopy. ^(b)Based on isolated polymer yield. ^(c)Turnoverfrequency = mol PO · mol Co⁻¹ · h⁻¹. ^(d)Selectivity for PPC overpropylene carbonate. ^(e)Determined by gel permeation chromatographycalibrated with polystyrene standards in THF. ^(f)Determined by ¹³C NMRspectroscopy. [PPN] = bis(triphenylphosphine)iminium. [OBzF₅] =pentafluorobenzoate.

TABLE 7 PO:[PPN]Cl: [(R,R)-(salen- Time Yield^(b) TOF^(c)Selectivity^(d) M_(n) ^(e) Head-to-Tail Entry 1)CoOBzF₅] (h) (%) (h⁻¹)(% PPC) (kg/mol) M_(w)/M_(n) ^(e) Linkages^(f) (%) 1 2000:1:1 1 31 64099 26.8 1.13 94 2 2000:1:1 2 52 520 >99 43.0 1.10 93 3 2000:1:1 6 59 20056 41.4 1.36 93 4 2000:2:1 2 53 530 97 33.9 1.08 93 5 2000:0.5:1 2 36360 >99 46.3 1.07 94 ^(a)Polymerizations run in neat rac-propylene oxide(PO) at 22° C. with 200 psi of CO₂. All product poly(propylenecarbonate) (PPC) contains ≧98% carbonate linkages as determined by ¹HNMR spectroscopy. ^(b)Based on isolated polymer yield. ^(c)Turnoverfrequency = mol PO · mol Co⁻¹ · h⁻¹. ^(d)Selectivity for PPC overpropylene carbonate. ^(e)Determined by gel permeation chromatographycalibrated with polystyrene standards in THF. ^(f)Determined by ¹³C NMRspectroscopy. [PPN] = bis(triphenylphosphine)iminium. [OBzF₅] =pentafluorobenzoate.

WORKING EXAMPLE XXV Effect of Cocatalyst

Copolymerizations were carried out with variations in catalyst andco-catalyst with results as set forth in Table 8 below:

TABLE 8 Time Yield TOF Selectivity M_(n) Head-to-Tail Entry^(a)Cocatalyst (h) (%)^(b) (h⁻¹)^(c) PPC:PC^(d) (kg/mol) M_(w)/M_(n)Linkages (%) 1 None 24 trace NA NA NA NA NA 2 [PPN][BPh₄] 24 trace NA NANA NA NA 3 [PPN]Cl 0.5 30 600  99:1 9.8 1.18 94 4 [PPN][OBzF₅] 0.5 36720 >99:1 15.9 1.16 94 5 [PPh₄]Br 0.5 24 480  96:4 6 [PPh₄]Cl 0.5 25 550 97:3 8.6 1.19 94 7 [n-Bu₄N]Cl 2 29 150 >99:1 6.6 1.15 93 8 N(CH₂CH₃)₃ 238 190 >99:1 18.5 1.17 9 N((CH₂)₇CH₃)₃ 2 35 175 >99:1 18.1 1.14 93^(a)Polymerizations run with catalyst [(R,R)-(salen-1)CoOBzF₅] in neatrac-PO with [PO]:[Co]:[cocatalyst] = 1000:1:1 at 22° C. with 100 psi ofCO₂. ^(b)based on isolated PPC yield. ^(c)TOF for PPC. ^(d)Selectivityfor PPC over PC. ^(e)[PO]:[Co]:[cocatalyst] = 2000:1:1.^(f)[PO]:[Co]:[cocatalyst] = 500:1:1.

WORKING EXAMPLE XXVI Copolymerization at 10 psi of CO₂

The [(R,R)-(salen-1)CoOBzF₅/[PPN]Cl catalyzed PO/CO₂ copolymerizationcarried out at 10 psi resulted in a TOF of 160 h⁻¹, affording 32% yieldof PPC.

WORKING EXAMPLE XXVII

Use of R₁ substituted ethylene oxides in the copolymerization using[(R,R)-(salen-1)CoOBzF₅]/[PPN]Cl

TABLE 9 Carbonate Time Yield^(b) Polymer: TOF^(d) Linkages^(e) M_(n)^(f) Head-to-Tail Entry R₁ (h) (%) Cyclic^(c) (h⁻¹) (%) (kg/mol)M_(w)/M_(n) ^(f) Linkages^(g) (%) 1 CH₂OCH₃ 6 56 85:15 93 4.7 1.42 2CH₂OPh 8 40 92:8 50 13.1 1.19 3 CH₂OSi^(t)Bu(CH₃)₂ 50 90 81:19 2 45.41.15 87 4^(h) CH═CH₂ 48 58 91:9 24 >99 44.8 1.15 52 5^(i) CH₂CH₃ 2 3995:5 194 98 24.1 1.15 >99 6 CH₂CH₂CH₂CH₃ 6 58 74:26 97 94 20.7 1.22 7 H2 80 99:1 400 80 32.1 1.18 NA ^(a)All reactions were performed in neatrac-epoxide with catalyst [(R,R)-(salen-1)CoOBzF₅] and cocatalyst[PPN]Cl with [epoxide]:[Co]:[[PPN]Cl] = 1000:1:1 at 22° C. with 100 psiof CO₂ unless otherwise noted. ^(b)Based on total polymer + cycliccarbonate.Variations

The foregoing description of the invention has been presented describingcertain operable and preferred embodiments. It is not intended that theinvention should be so limited since variations and modificationsthereof will be obvious to the skilled in the art, all of which arewithin the spirit and scope of the invention.

1. A compound of formula: